Image-based video is essentially a slide show of images with motion, e.g. panning and zooming applied to still images, and transitions applied between images, to create a moving picture effect. When creating an image-based video, an input source image may have a different aspect ratio than the aspect ratio of the video output being generated. Such aspect ratios represent the relation of the width to the height of a picture. The aspect ratio of the video is a function of the video port, for example, the aspect ratio of 4:3. When the aspect ratio of the input image is not the same as that of the video port, a technique called “enveloping” is typically used to generate the image-based video. If the full picture needs to be displayed in the video, enveloping causes black borders to appear in the video.
For example, FIG. 1 shows an exemplary video frame 100 with an aspect ratio of 640×480 (width×height) that encapsulates a source image 102 with an aspect ratio of 640×300). Since the aspect ratio of the video frame is 4:3 and the aspect ratio of the image is not the same (the source image has a different height), conventional techniques envelope the image with black borders (e.g., borders 104 and 106). Displaying such black borders when playing an image-based video is aesthetically unpleasing, and can substantially detract a user's viewing experience.